Radio frequency identification (RFID) technology relates basically to the field of local communication technology and more particularly local communication technology involving electromagnetic and/or electrostatic coupling technology. Electromagnetic and/or electrostatic coupling is implemented in the radio frequency (RF) portion of the electromagnetic spectrum, using for example radio frequency identification (RFID) technology, which primarily includes radio frequency identification (RFID) transponders also denoted as radio frequency identification (RFID) tags and reader devices for radio frequency transponders also denoted for simplicity as radio frequency identification (RFID) readers.
Originally, radio frequency identification (RFID) technology has been developed and introduced for electronic article surveillance, article management purposes and logistics primarily for replacing bar code identification labels which are used for article management purposes and logistics up to now. A typical implementation of a state of the art radio frequency identification (RFID) transponder is shown with respect to FIG. 1. A typical radio frequency identification (RFID) transponder module 10 includes conventionally an electronic circuit, depicted exemplary as transponder logic 11, with data storage capacity, depicted herein as transponder memory 12, and a radio frequency (RF) interface 235 and high frequency (HF) interface, respectively, which couples an antenna 13 to the transponder logic 11. The radio frequency identification (RFID) transponders are typically accommodated in small containers. Depending on the requirements made on envisaged applications of the radio frequency identification (RFID) transponders (i.e. the data transmission rate, energy of the interrogation, transmission range etc.) different types are provided for data/information transmission at different radio frequencies within a range from several 10-100 kHz to some GHz (e.g. 134 kHz, 13.56 MHz, 860-928 MHz etc; only for illustration). Two main classes of radio frequency identification (RFID) transponders can be distinguished. Passive radio frequency identification (RFID) transponders are activated and energized by radio frequency identification (RFID) readers, which generate an interrogation signal, for example a radio frequency (RF) signal at a certain frequency. Active radio frequency identification (RFID) transponders comprise own power supplies such as batteries or accumulators for energizing.
On activation of a radio frequency identification (RFID) transponder by a radio frequency identification (RFID) reader, the informational contents stored in the transponder memory 12 are modulated onto a radio frequency (RF) signal, which is emitted by the antenna 13 of the radio frequency identification (RFID) transponder to be detected and received by the radio frequency identification (RFID) reader. Typical state of the art radio frequency identification (RFID) transponders correspond to radio frequency identification (RFID) standards such as the ISO 14443 type A standard or the Mifare standard. In accordance with the applicational purpose of a radio frequency identification (RFID) transponder, the information or data stored in the transponder memory may be either hard-coded or soft-coded. Hard-coded means that the information or data stored in the transponder memory 13 is predetermined and unmodifiable. Soft-coded means that the information or data stored in the transponder memory 13 is configurable by an external entity. The configuration of the transponder memory may be performed by a radio frequency (RF) signal via the antenna 13 or may be performed via a configuration interface, which allows for connection with the transponder memory 13.
More particularly, in the case of a passive radio frequency identification (RFID) transponder (i.e., having no local power source), the radio frequency identification (RFID) transponder is conventionally energized by a time-varying electromagnetic radio frequency (RF) signal/wave generated by the interrogating radio frequency identification (RFID) reader. When the radio frequency (RF) field passes through the antenna coil associated with the radio frequency identification (RFID) transponder, a voltage is generated across the coil. This voltage is ultimately used to energize the radio frequency identification (RFID) transponder, and enables back transmission of information from the radio frequency identification (RFID) transponder to the radio frequency identification (RFID) reader, which is sometimes referred to as back-scattering.
Interest in various radio frequency (RF) tagging technologies has recently grown significantly resulting to development of various radio frequency (RF) tagging applications outside the conventional manufacturing line and electronic article surveillance applications.
As RF-tagging technologies are considered to become as one technology providing short-range interaction applications in the near future, especially in mobile communication environment, the basic nature of the RF-tagging technologies (passive communication, no means for “true” duplex data transfer) is becoming more of an issue to be considered in connection with applications relating to interactivity.
As soon as a portable device equipped with a radio frequency identification (RFID) transponder logic receives an interrogation signal upon entering into a coverage area of radio frequency identification (RFID) reader device, the radio frequency identification (RFID) transponder responds to the interrogation signal by back-transmitting of radio frequency (RF) signals embedding data stored in connection with the radio frequency identification (RFID) transponder. The radio frequency identification (RFID) reader device may be capable of initiating or providing various services or applications based on the data received from the radio frequency identification (RFID) transponder. However, the portable device equipped with a conventional radio frequency identification (RFID) transponder circuit does not have any means to determine whether the data of the radio frequency identification (RFID) transponder have been read by the external radio frequency identification (RFID) reader device for performing subsequent operations based on this determination.
Moreover, when considering various transaction applications (such as ticketing services) security and privacy issues relating especially to ticket redemption process needs to taken into account. For instance a user may have purchased a mass transit ticket valid for a certain time-period or a serial ticket with multiple one-way- or roundtrips. When such a ticket is implemented by way of a radio frequency identification (RFID) transponder providing the ticket information, the information typically includes some private user-related information (e.g. social-security number, date of birth, customer identification or like) and/or other confidential and secure information (e.g. ticket identifier or like). Such sensitive information is preferably kept secret in order to prevent possible misuse. In order to keep such sensitive information hidden (invisible) to any potentially hostile radio frequency identification (RFID) reader devices, it would be advantageous if the mobile terminal equipped with the radio frequency identification (RFID) transponder circuit, which is capable to determine whether the data sorted in the radio frequency identification (RFID) transponder has been read-out in order to remove the sensitive data from the radio frequency identification (RFID) transponder to enhance security.